Shielding container for radioactive sources



lJune 16, 1953 v J, F; 'YOUNG 2,642,541

l SHIELDING CONTAINER FoR RAD1QACT1VE SOURCES Filed Nov. 29, 1951 2sheets-sheet 1 Inventar,

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June 16, 1953 J. F. YOUNG SHIELDING coNTAINER Foa RAnIoAcTIvE souRcEs 2sheets-sheet 2 Filed Nov. 29, 1951 l 2.7 Inventor, rfozn if lazgy,

Patented June 16, 1953 UNITED SHIELDING GONTAINER FOR RADIOACTIVESOURCES John F. Young, Salem, Mass., assigner to Tracerlab, Inc.,Boston, Mass., a corporation of Massachusetts Application November 29,1951, Serial No. 258,818

(Cl. Z50-108) 11 Claims. l

This invention relates to containers for radioactive sources such asthose used in industrial radiography. More particularly it is concernedwith a new and improved container for safely storing and transportingsources of high radiation intensity, such as Cobalt-60 and having aunique provision for shielding the radiographer even when the containeris open for removing or replacing the source.

Non-destructive testing of materials has become increasingly common withthe availability of high intensity gamma emitters, e. g., Cobalt-60 as asubstitute for the very expensive radium compounds heretofore in use.This type of radiography utilizes the -absorption properties of densematerials to form latent shadow images on i'llm sensitive to thepenetrating gamma rays emitted by the isotope. Thick specimen sectionsinterposed between the source and lm produce light areas on thedeveloped film, whereas progressively darker areas are produced Wheneverthe total thicknesses are less. In solid castings, then less densevolumes such as gas holes would appear as dark spots on the developedfilm.

The use of these high intensity sources presents the problem ofprotection to the radiographer from excessive radiation dosage. Remotehandling equipment has been devised to remove the source from itsshielding container and place it into position for radiographic test.The present art does not, however, have a shielding container whicheffectively protects the radiographer while he is opening the containerto allow for removal of the source.

The primary object of the present invention is to provide a new andimproved shielding oontainer for radioactive sources to minimizeradiation exposure from the source to the operator in either opening orclosing the container and removing or replacing the source.

Another object of the invention is the provision of a compact, sturdy,upright and readily accessible container for radioactive sources,adequately shielded to meet all safety requirements.

With the foregoing in mind, the invention is featured by the provisionof a container of the type described including a generally sphericalshield composed of lead or other suitable material relativelyimpermeable to gamma rays, and having a cavity near its center forholding a capsule containing the radioactive source and a slottedopening from its periphery to the cavity giving access to the capsule, ashielding cover composed of the same material fitting the slottedopening and hinged to permit swinging from a closed position completelyshielding the source to an open position where it still serves to shieldthe operator from direct radiations from the source. The shielding coveris so proportioned and arranged that in closed position it will placebetween the source and the outside wall of the cover a thickness ofshielding material comparable to the thickness of the other walls of theshielding sphere. In addition means are provided facilitating theraising of the cover without exposure of the operator to directradiations from the source and a stop for holding the cover in itspredetermined open position above described. Furthermore, a convenientlocking arrangement is provided for locking the cover secure in closedposition to prevent tampering by unauthorized personnel.

Still other objects, features and advantages of the invention willbecome apparent from the following detailed description of a preferredembodiment thereof taken in connection with the annexed drawings, inwhich like numerals refer to like parts in the several views, and inwhich:

Fig. 1 is a plan View of a container embodying the invention with thecover in closed position, the open position of the latter beingindicated by dash and dot lines;

Fig. 2 is a front elevation of the same;

Fig. 3 is a side elevation of the same;

Fig. 4 is an enlarged sectional view on line 4-4 of Fig. 1;

Fig. 5 is a fragmentary elevational view showing only the lead shieldingsphere and illustrating its central source holding cavity; and

Fig. 6 is an elevational view with portions cut away of the wedge-shapedcover which is adapted to t the corresponding opening in the sphericalshield.

The shielding container of the invention comprises a generally sphericalshielding member, which may be a lead casting having a minimum lead wallthickness of 37/8 inches for sources up to 500 millicuries. Generally atthe center of the sphere I0 is located a cylindrical cavity I2 forreceiving a lead insert I3 in Which the source holder I4 is removablyheld. The usual source I6 consists of the radioactive material sealed inits holder, a ferromagnetic stainless steel capsule I4. The capsuleserves the function of preventing dispersion of the radioactiveCobaltand provides for absorption of the weak beta radiation therefromto give a pure gamma source.

The container proper I0 is provided wi-th a wedge-shaped slotted openingI9 having a horizontal floor Il ush with the upper rim of the 3 openingI2 which holds the insert I3. The opening I9 is arranged to receive thecover I8 in a manner hereinafter more fully described.

The cover I8 which is a wedge or pie shaped segment of the shieldingsphere I rotates on the hinge pin 20 which is supported by the hingeplates 22a and 22h forming a part of the outer steel framework. Openingof the cover allows positioning of the source within the shieldingsphere I8. As the radiographer opens the container the cover I8 servesas a shield so that he is not exposed to the direct radiation'even whilehandling the source. A properly trained loperator can keep the shieldand cover between'his person and the source during most, if not all, ofthe duration of the radiography procedure until the same is again safelyenclosed in the con'- tainer. This unique safety feature is of Aextremepractical importance in View of the limited tolerance of the human bodyto penetrative radiations such as gamma rays.

The cover stop rod 24 fun-ctions to maintain the cover I8 in asatisfactory shielding position while in its open position. The coverlift 26 enables the radiographer readily to open the unit by lifting therather heavy cover I8. The cover consists of an outer framework 2'I ofsteel about a cored cavity which is filled with lead as indicated by thenumeral 28.

Serving as an outer protective framework for the shielding sphere is thecylindrical steel base 30, the bottom steel plateA 32 which is welded tothe base, the two hinge plates 22a and 22o and the lifting lug plates34a and .34h which are provided with handling holes 35. The hinge plateshave holes 36 located above the cover lift 26 so that once the source iswithin the; shielding container means are available to lock the unitWith a padlock or other securing means. All the abutting elements of thesteel frameworks are welded together to form a rugged unitary structure.

It will be noted that the lead container I8 while generally spherical incontour is nevertheless somewhat elongated in its vertical dimension.Furthermore, the horizontal floor II of the wedge-shaped cover-receivingopening I9 is somewhat above the horizontal center line of the sphere.This construction permits the locating of the cavity I2, lead adapterI3- and capsule I4 in such a way that the source I3 will be close to thegeometrical center of the unit, with a maximum thickness of lead on allsides when the cover is closed.

While I have herein disclosed and described a source-holding capsulehaving a particular configuration, the upper end (as seen in Fig. 4)thereof being enlarged to facilitate handling, it will be understoodthat the container ofthe invention may be adapted for holding sources ofother dimensions by providing lead inserts I3 having sockets of avariety of sizes and shapes. In each case the adapter I3 preferably isprovided with a socket precisely tting the source capsule andadditionally provides shielding so that a minimum weigh-t of outershielding is required.

In the use of the container, the radiographer may transport the same tothe desired location by means of the handling holes 35. lWhen thesubjects to be radiographed have been prepared for exposure the lid I8is opened by means of a remote handling tool using the ledge 26. Thecover will remain suspended in open position by reason of engagementWith the bar 24, as in- 4 dicated by the dash and dot lines in Figs. 13. The radiographer, operating from a position behind the open cover,and using a remote handling tool such as a magnetic holder, may removethe capsule I4 from its seat in the insert I3 and place it in properposition to expose the 'articles to be radiographed. During the openingof the container and the removal and replacement of the source, theoperator is shielded to a maximum degree from harmful radiations bycontainers spherical walls and the open cover in any of its positionsfrom fully closed to fully opened.

The container, according to the invention, is adapted for transportingradioactive source of high intensity from one place to another with nodanger to persons in the vicinity. The thickness of the lead walls mayoptionally be changed to furnish adequate shielding for sources ofgreater or lesser activity as desired. Furthermore, the lockingarrangement is such as to prevent .opening by unauthorized personnelduring transport or storage. The shielding Acontainer may beappropriately dimensioned to reduce the intensity of radiations from theparticular source at its outer surface below the maximum levelspermitted for transporta-tion by common carrier. l

The unique shielded container of the invention is not limited to usagein the radiography art, but may be used anywhere that radioactivesources are to be transported or stored ready for convenient use with aminimum of danger to personnel.

While I have herein shown and described a container according to theinvention employing lead as a shielding medium, it will be understoodthat other relatively radiation impermeable materials may be usedwithout departing from the invention. Furthermore, while I have hereindisclosed and described a preferred embodiment of the invention it Willbe understood that the same is susceptible of various modifications andchanges Within the spirit and scope of the appended claims.

I claim:

1. A shielding container for the storage and transportation ofradioactive sources which comprises, in combination, a generallyspherical member composed of radiation shielding material, said memberhaving a cavity located generally at its center for removably holding aradioactive source and having a Wedge-shaped slotted opening from itsperiphery to said cavity permitting access to the latter, a cover alsocomposed of radiation shielding material fitting said slotted opening,and a hinged mounting for said cover permitting swinging thereof about ahorizontal axis from a position lling said opening and shielding saidysource through a predetermined angle to a second position permittingaccess to said source while affording a maximum of shieldingprotectionto the operator during removal from and replacement in said cavity ofsaid source.

2. A shielding container for the storage and transportation ofradioactive sources which comprises, in combination, a generallyspherical me. ber composed of radiation shielding material, acylindrical metallic holder in which said member is mounted, said holderhaving portions extending over` the upper portions of said member, saidmember having a cavity located generally at its center for removablyholding a radioactive source and having a wedge-shaped slotted openingin its upper portion extending from its periphery to said cavitypermitting access to the latter, a cover, also composed of radiationshielding material conforming in shape to said slotted opening andhingedly mounted on an upwardly extending portion of said metallicholder permitting swinging thereof about a horizontal axis from aposition filling said opening and shielding said source through apredetermined angle to a second position permitting access to saidsource while affording a maximum of shielding protection to the operatorduring removal from and replacement in said cavity of said source.

3. Apparatus in accordance with claim 2 including a stop bar mounted onan upwardly extending portion of said metallic holder for supportingsaid cover open in a predetermined position.

4. Apparatus in accordance with claim 2 in which said cover is providedwith an overhanging ledge to facilitate opening thereof.

5. Apparatus in accordance with claim 2 in which the upwardly extendingportions of said metallic holder include a pair of flanges adjacent saidslotted opening, said flanges having means permitting the locking ofsaid cover in closed position.

6. Apparatus in accordance with claim 2 in which said wedge-shapedopening has verticalrear and side walls and a horizontal Hoor, saidcavity opening into a rear portion of the latter, said floor being abovethe center of said member, whereby said source, when positioned in -saidcavity, will be located close to the geometrical center of said member.

7. A shielding container for the storage and transportation ofradioactive sources comprising, in combination, a generally sphericalmember formed of radiation shielding material, said member having awedge-shaped opening extending from its periphery with vertical rear andside walls anda horizontal floor, a cover also formed of radiationshielding material conforming in shape to said opening, and meanshingedly mounting said cover along the upper edge of said rear wall ofsaid opening permitting swinging of said cover from a position llingsaid opening through an angle of approximately 180 degrees, said memberhaving a cavity located generally at its center and communicating withthe horizontal floor of said opening for removably `holding aradioactive source.

8. A shielding container for the storage and transportation ofradioactive sources comprising, a generally spherical member formed ofradiation shielding material, said member having a cavity formedsubstantially at its geometric center for removably containing aradioactive source and a wedge-shaped opening, extending from itsperiphery with Vertical rear and side walls and a horizontal floor, saidcavity communicating with the floor of said opening near theintersection of said floor and said rear Wall, said side walls beingparallel to each other and spaced equidistantly on either side of avertical axis through the center of said member, said rear wall beingperpendicular to said side walls and displaced from said vertical axiswhereby the floor of said opening is somewhat longer than said rearwall, a cylindrical metallic holder in which said member is mounted,said holder having portions extending upwardly beyond said member, acover conforming in shape to said opening also formed of radiationshielding material hingedly mounted along the upper edge of said rearwall on an upwardly extending portion of said holder permitting swingingthereof from a position lling said opening through an angle ofapproximately 180 degrees to an open position, said cover when in theopen position permitting access to said source while affording a maximumof shielding protection to the operator during removal from andreplacement in said cavity of said source,

9. Apparatus in accordance with claim 8 including a horizontal stop barmounted on an upwardly extending portion of said metallic holder forsupporting said cover in the open position.

l0. Apparatus in accordance with claim 9 in which the upwardly extendingportions of said metallic holder further include a pair of flangesadjacent to the side walls of said opening, said flanges including meanspermitting the locking of said cover in the closed position.

1l. A shielding container for the storage and transportation ofradioactive sources comprising, a generally spherical block of radiationshielding material, said block having a wedgeshaped opening formedtherein extending from its periphery with vertical rear and side wallsand a horizontal floor, said side walls being parallel to each other andspaced equidistantly on either side of a vertical axis through thecenter of said block, said block also having a cylindrical cavity formedtherein coaxial with said vertical axis and communicating with the floorof said wedge-shaped opening, a protective framework for said blockincluding a cylindrical metallic base having a pair of hinge platesextending upwardly therefrom beyond the upper portion of said block,said hinge plates being arranged adjacent to the side walls of saidopening, a cover conforming in shape to said opening also formed ofradiation shielding material hingedly mounted along thel upper edge ofthe rear wall thereof between said hinge plates permitting swingingthereof from a closed position filling said opening to an open position,a stop bar JOHN F. YOUNG.

References Cited in the file of this patent UNITED STATES PATENTS NameDate Gilks l May 1, 1951 Number

